The experiments proposed will examine the effects of stress on the physiological responses of the heart, vascular smooth muscle, liver and intestine to epinephrine. The effects of stress will also be studied with respect to the effects of epinephrine on neuromuscular transmission. Hypophysectomized rats will be used and the manner by which growth hormone and glucocorticoids protect against stress will be examined. Since stress produces caridovascular collapse in hormonally deficient animals as well as decreased sensitivity of adipose tissue to the lipolytic actions of epinephrine, we will examine the possibility that the cyclic AMP system which mediates both lipolytic and cardiovascular responses to catecholamines, may be the site of stress related impairments of homeostasis. The possibility that adrenal glucocorticoids and growth hormone offer protection against stress by maintaining the integrity of the cyclic AMP system will also be explored.